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Mars Viking Geologic Map I-2107 of North Kasei Valles

The north Kasei Valles area merits detailed geologic study
because it contains part of a large channel system whose
age can be determined relative to geologic units that range
in age from the early intermediate (Early Hesperian) to the
very late (Late Amazonian) periods of Martian history.
Also, many geomorphic features in the map area suggest
changes in water level and multiple erosional events
associated with the Kasei Valles system. Later erosional
events are indicative of spring sapping; small-scale,
ground-water runoff; and water-mobilizing debris flow.
Therefore, this large-scale mapping has increased our
understanding of the history of hydrologic processes of
Mars (Chapman and Scott, 1989). For these reasons, part of
the area is a candidate site for a sample-return mission to
the planet.

Data Status and Quality

These data are believed to be logically consistent, though no tests were performed.

Completeness Report

Maps were completed on Viking-era basemaps.

Process Description

This map was compiled on a Viking 1:500, 000-scale
photomosaic base (U.S. Geological Survey, 1984). Some maps
units correspond or are partly equivalent to units on
smaller scale maps (Milton, 1974; Scott and Tanaka, 1986),
and the formal terminology of geologic units proposed by
Scott and Tanaka (1986) was followed where feasible.
However, in many places interpretations and contacts have
been revised to reflect information visible on higher
resolution images whose geomorphologic details were
clarified by spatial filtering (Condit and Chavez, 1979).
The depths of channels, thicknesses of geologic units, and
heights of scarps were obtained in places by using
photoclinometric methods of Davis and Soderblom (1984). The
relative ages of geologic units and of various geomorphic
features, such as ridges, depressions, channels, crevices
forming rectilinear patterns, streamlined mounds, and
grooves, were established by stratigraphic relations and
supported by crater counts. The stratigraphic positions of
erosional units represent the time of their modification
relative to other material units whose positions in
sequence reflects their time of emplacement. Erosional
units may thus consist of older material that is in place
but has been highly modified by later processes (Milton, 1974).

Map preparation was on mylar or acetate made from USGS negatives. All features were scanned at 50 microns and then vectorized and attributed in ArcGIS.